780MPa-level low-carbon and low-alloy TRIP steel and rapid heat treatment method thereof

A rapid heat treatment, low alloy technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of high manufacturing costs and high equipment requirements, and achieve the effects of reducing production costs, reducing energy consumption, and improving tensile strength

Active Publication Date: 2019-06-28
BAOSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Chinese patent CN102312157B proposes the general process of TRIP steel production process, and limits the austenitization process to the high temperature structur...

Method used

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  • 780MPa-level low-carbon and low-alloy TRIP steel and rapid heat treatment method thereof
  • 780MPa-level low-carbon and low-alloy TRIP steel and rapid heat treatment method thereof
  • 780MPa-level low-carbon and low-alloy TRIP steel and rapid heat treatment method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] The chemical composition of the selected raw material steel is calculated by weight percentage: C-0.16%, Mn-1.6%, Si-1.4%, and the balance is Fe and unavoidable impurity elements. The steel plate before heat treatment is cold-rolled strip steel, and the cold-rolling reduction rate is 65%. The microstructure of steel plate after cold rolling is composed of pearlite and ferrite.

[0062] The heat treatment process steps are as follows:

[0063] 1) Heat the steel plate to 770°C at a heating rate of 300°C / s and keep it warm for 60s;

[0064] 2) Cool the steel plate to 410°C at a cooling rate of 40°C / s and keep it warm for 200s;

[0065] 3) Rapid cooling from 410°C to room temperature at 50°C / s.

[0066] The whole process of the above heat treatment takes about 278s, and the microstructure of the obtained TRIP steel is as follows: figure 1 As shown, the bainite is obviously refined and is in the submicron granular form; the austenite is distributed in an island shape; and ...

Embodiment 2

[0070] The chemical composition of the selected raw material steel is calculated by weight percentage: C-0.22%, Mn-2.2%, Si-1.2%, and the balance is Fe and unavoidable impurity elements. The steel plate before heat treatment is cold-rolled strip steel, and the cold-rolling reduction rate is 55%. The microstructure of steel plate after cold rolling is composed of pearlite and ferrite.

[0071] The heat treatment process steps are as follows:

[0072] 1) Heat the strip steel plate to 800°C at a heating rate of 30°C / s and keep it warm for 90s;

[0073] 2) Cool the steel plate to 430°C at a cooling rate of 100°C / s and keep it warm for 250s;

[0074] 3) Rapid cooling from 430°C to room temperature at 100°C / s.

[0075] The whole process of the above heat treatment takes about 374s, and the microstructure of the obtained TRIP steel is as follows: image 3 As shown, the bainite particle size is very small; the austenite is distributed in an island shape; the bainite and austenite ...

Embodiment 3

[0079] The chemical composition of the selected raw material steel is calculated by weight percentage: C-0.18%, Mn-2.0%, Si-1.6%, and the balance is Fe and unavoidable impurity elements. The steel plate before heat treatment is cold-rolled strip steel, and the cold-rolling reduction rate is 65%. The microstructure of steel plate after cold rolling is composed of pearlite and ferrite.

[0080] The heat treatment process steps are as follows:

[0081] 1) Heat the steel plate to 850°C at a heating rate of 200°C / s and keep it warm for 40s;

[0082] 2) Cool the steel plate to 420°C at a cooling rate of 80°C / s and keep it warm for 300s;

[0083] 3) Rapid cooling from 420°C to room temperature at 150°C / s.

[0084] The whole process of the above heat treatment takes about 352s, and the microstructure of the obtained TRIP steel is as follows: Figure 5 As shown, the size of bainite is obviously smaller; the austenite is distributed in an island shape; the bainite and austenite are ...

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Abstract

The invention provides 780MPa-level low-carbon and low-alloy TRIP steel and a rapid heat treatment method thereof. The steel comprises the following chemical components in percentage by mass: 0.16-0.22% of C, 1.2-1.6% of Si, 1.6-2.2% of Mn, and the balance Fe and other inevitable impurities. The method comprises the steps of rapidly heating, maintaining temperature within short time, and rapidly cooling. According to the steel and the method, the recrystallizing and phase changing processes in the heating and the phase change process in cooling are controlled, thus a three-phase structure thatbainite and austenite are uniformly distributed on a ferrite substrate can be obtained; the average crystal grain size of bainite and austenite is 1-3 microns; bainite is of a submicron particle form; austenite is of an island uniformly-distributed equiaxial crystal grain form; the whole three-phase structure comprises 35-75% by volume of bainite, 10-60% by volume of ferrite, and 5-15% by volumeof austenite; with the adoption of the rapid heat treatment, the mechanical performance of the material is improved while the heat treatment efficiency is improved; and the material performance area range is expanded.

Description

technical field [0001] The invention belongs to the technical field of rapid heat treatment of materials, and in particular relates to a 780MPa low-carbon low-alloy TRIP steel and a rapid heat treatment method thereof. Background technique [0002] With the gradual improvement of people's awareness of energy conservation and material safety in service, the use of high-strength steel, especially advanced high-strength steel, is increasing. This also makes iron and steel enterprises and scientific research institutes pay more and more attention to the development of advanced high-strength steel. In order to further improve the strength-plastic product of steel products, the development of advanced high-strength steel represented by TRIP (phase transformation induced plastic deformation) steel has been paid more and more attention. The cold rolling heat treatment process of cold rolled TRIP steel consists of two stages of austenitizing annealing and bainite isothermal treatmen...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C21D9/46C21D9/52
Inventor 孟庆格李俊王健张利祥徐德超
Owner BAOSHAN IRON & STEEL CO LTD
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